Sonic vibration spot welder



Dec. 28, 1965 F. A. WYCZALEK 3,225,997

SONIC VIBRATION SPOT WELDER Filed July 31, 1962 United States Patent3,225,997 SONIC VIBRATION SPOT WELDER Floyd A. Wyczalelr, Birmingham,Mich, assignor to General Motors Corporation, Detroit, Mich, acorporation of Delaware Filed July 31, 1962, Ser. No. 213,813 Claims.(Cl. 228-1) This invention relates to a welder and more particularly toa method and apparatus for utilizing vibratory energy for bonding two ormore metallic members together.

The use of vibratory energy for the purpose of welding or bondingseparate metallic sheet members to each other is not new. The prior artteaches the use of an electrically driven transducer for causingfrictional heat to be generated between the intersurfaces of twocontacting sheets of metal so as to complete a weld. The difficulty ofthis device, however, has been that a transducer or vibration generatorcomposed of magneto-striction bars or the like is incapable of driving abody in high power applications. One reason being that this form ofvibration generator is inherently limited to motion of only a few feetper second due to limitation imposed by elastic strain limits. Hence, tocouple a magneto-strictive type generator to a resonant member resultsin a practical limit to the amount of power which can be transferred tothe driven member.

Accordingly, one object of the present invention is to provide a methodand apparatus for bonding two members together in which vibratory energyis used to complete the weld with the vibratory energy being efficientlytransmitted to the weld area through a resonant member driven by a highpower mechanical vibrator.

Another object of the present invention is to provide a method andapparatus for welding sheets of metal together with one of the membersbetween which the sheets are clamped, so associated with a vibrationgenerator that the latter generates a rotating force vector normal tothe longitudinal axis of the members so that torsional or oscillatorymodes of vibration or a combination of the two results.

The above and other objects are obtained in accordance with theinvention by a device having a column or vibration transmitting memberassociated with one or more vibrators capable of delivering large forcesto the member at the resonant frequency thereof so as to supply anincreased amount of energy in the welding area. This is accomplished byhaving the vibratory column dimensioned to resonate in a flexural modeand suitably supported on a base which serves as a reaction mass topreclude any energy dissipation. One or more fluid driven vibrators areconnected to the member at the flexural antinode thereof in a positionoffset from the longitudinal axis thereof so as to provide a rotatingforce vector that causes a desired bending of the column. A reactionmass, serving as a reflector anvil, is positioned in vertical alignmentwith the vibratory column and includes mechanism for exerting apredetermined amount of force in a localized area of the sheets beingwelded.

A more complete understanding of the subject invention can be derivedfrom a perusal of the detailed description taken in conjunction with theaccompanying drawings in which:

FIGURE 1 is an elevation view, with portions broken away, of a weldingdevice incorporating the present invention;

FIGURE 2 is a view taken on lines 22 of FIGURE 1;

FIGURE 3 is a fragmentary view taken on lines 33 of FIGURE 2;

3,225,9fi7 Patented Dec. 28, 1965 FIGURE 4 is a fragmentary view takenon lines 4-4 of FIGURE 3;

FIGURE 5 is a View similar to FIGURE 2 but in section showing thewelding device of FIGURE 4 employing a dual vibrator arrangement; and

FIGURE 6 is a view showing a modification of the dual vibratorarrangement of FIGURE 5.

Referring to FIGURE 1, a welding press is shown made in accordance withthe invention and comprising a vibration transmitting member 2 supportedby a base 4 and located in vertical alignment with a movable reflectoranvil 6. An air-operated mechanism 8 is fixed to a rigid cross beam 10and includes the conventional piston and rod connecting to the reflectoranvil 6 for moving the latter downwardly to coact with the member 2 forholding at least two sheets 11 of metal or other material therebetween.An air driven vibrator 12 is mounted to the member 2 for transmittingvibratory energy to the welding zone and is energized by compressed airsupplied under the control of a valve 13 and originating in a source 14connected with the member 2 by the conduit 16.

The member 2 comprises cylindrical column portions 18 and 20,respectively, with the upper column 20 being of a reduced diameter andextending vertically upwardly from the lower portion 18. The column 20constitutes the vibratory portion of the member 2 and has a laterallyextending integral support arm 22 having a circular opening 24 forsuitably accommodating the vibrator 12. A plug member 26 closes theupper end of a vertical air passage 28 formed in the column 20 andincludes a spherical bearing portion 27 for engagement with theunderside of one of the sheets 11 during the welding operation. The plugmember is made from a nickel alloy which has a low energy loss andpossesses good fatigue properties in addition to having thecharacteristics of thermal conductivity which is less than steel. Thelower end of the member 2 is supported on the base 4 by a pair ofBelleville springs 29 which rest on the base and serve to isolate themember 2 to minimize the energy loss therefrom when the vibrator isoperating. A pair of Belleville springs 31 are also interposed betweenthe anvil 6 and operating means 8 for the same purpose.

The air passage 28 extends through the center of the member 2 andcommunicates at a lower portion thereof with a transverse passage 30that connects with the compressed air conduit 16. Near its upper end,the passage 28 communicates with a second transverse passage 32 thatleads into the arm 22 and connects with an annular chamber 34circumferentially enveloping the vibrator 12.

The vibrator 12 includes a cylindrical housing 36 closed at the oppositeends thereof by apertured disks 38 and 40 which, together with thehousing, define a confining chamber 42 for a cylindrical roller-typemass 44. The arrangement is such that pressurized air flows from thesource 14 via the passages 30, 28, 32, and chamber 34 to dischargethrough a plurality of tangentially directed orifices 46 formed in thehousing 36 and surrounding the confining chamber 42. The air exits fromthe several orifices as a thin high velocity stream and impinges againstthe periphery of the roller to drive the latter in an orbital path aboutthe confining chamber. As the roll orbits about the chamber, it appliesa centrifugal force against the housing 36 at different points so as toproduce, in effect, a rotating force vector that acts in a directiontransverse to the longitudinal axis of the column 20 and transmitsvibratory energy thereto. For most efficient operation, the vibrator isdriven at a frequency equal to the resonant frequency of the column 20to create a fiexural standing-type wave in the latter. The column 20forms a fixed-hinged beam and the hinged boundary is formed by thewelding area defined by the contact surface between the anvil and plugmember. As is well known to those skilled in the art of vibrations,during standing wave vibration the points of minimum and maximumdeflection are termed nodal and antinodal points, respectively. For afixed-hinged beam, the end boundaries are nodes which are points of highforce and low velocity. The antinode, on the other hand, is a point oflow force and high velocity located between the nodes. In this case thevibrator 12 is mounted at the antinode.

To complete a welding operation with the present invention, two or moremetallic plates 11 are positioned as shown in FIGURE 1 between thereflector anvil 6 and the plug member 26 with the plates being heldtherebetween by a predetermined amount of force being applied by theoperating mechanism 8 which derives its pressurized air from the source14 or some other. It has been found that when welding a pair of metalplates, a preload is necessary to maintain the plates in a rigidposition and form a hinged-type node prior to exciting the vibrator 12so that vibratory energy may be transmitted to the metal. The vibratoris then energized by opening the valve 13 and providing pressurized airat a pressure and flow rate which causes the roller 44 to orbit aboutthe confining or working chamber to create a rotating force vector atthe resonant frequency of the column 20. Due to the offset position ofthe vibrator relative to the longitudinal axis of the column 20 and whenthe roller is in the position of FIGURE 4, a force vector as indicatedby A .in FIGURE 2 acts as a moment arm to torsionally twist the column20. Similarly, when the roller is at a point diametrically opposite tothat shown in FIGURE 4, a force B is produced as seen in FIGURE 2 totwist the column about its axis in an opposite direction. As the vectorrotates to a position where the roller contacts the housing .in linewith the longitudinal axis of the support arm, indicated by force arrowsC and D, an oscillatory bending is created in the column resulting in asimilar movement of the plug member. As should be apparent, the combinedtorsional and oscillatory movement of the plug member at the resonantfrequency of the column causes a scrubbing action against the sheetswhich results in a weld between the latter attributable to oxide filmbreakdown and/ or heating at the weld zone due to friction. As alludedto hereinbefore, it has been found that for most efficient operation ofthe present invention, the vibrators should be operated at a frequencyequal to the resonant frequency of the vibration transmitting column. Byso doing, the deflection and therefore energy delivered by the plugmember to the weld zone is at a maximum for a given amount of energybeing put into the system.

FIGURE shows a modification of the present invention which is similar tothe preferred embodiments; however, is provided with two rather than asingle vibrator. The vibrators 12 are mounted in support arms 22' whichin this instance extend from opposite sides of the column and areconnected to the air passage 28' by a diagonal passage 32 thattangentially meets the annular air chambers 34 at opposite sides of thelongitudinal axis of the support arms 22'. Because of this arrangement,when pressurized air is applied to each of the vibrators, the associatedrollers 44 are driven in a counterclockwise direction at a phasedifference of 180 so as to cancel out any forces acting along thelongitudinal axis of the support arms, however the forces provide acouple about the column 20' when the rollers are acting in any directionother than along the support arm axis. The force couple acting on thecolumn 20 causes resonant torsional twisting of the latter in alternatedirections as indicated by the arrows E and F. To weld two sheets ofmetal with this device, of course, the procedure would be identical tothat described above except that with this device the vibrators woulddevelop a pure torsional movement of the column 20 and energy developedby this movement would be transferred to the welding zone by the plugmember 26 to complete the Weld. For best welding results, it has beenfound that the bearing portion 27 of the plug member should be formed soas to have an annular contact surface for engaging the outer surface ofone of the sheets 11. Thus, the completed weld would leave a ring-typeimpression in the sheets.

FIGURE 6 shows a further modification of the invention, whichessentially differs from the above modification by the disposition ofthe air passages 32 in an inverted V form so that the ends thereofconnect with the respective air chambers 34" of the vibrators on thesame side of the longitudinal axis of the support axis. With thisarrangement, the rollers 44" are driven in directions on posite to eachother so that the forces produced thereby eliminate any torsionaltwisting of the column and produce only an oscillating movement thereofin a direction normal to the longitudinal axis of the support arms asindicated by the arrows G and H. Thus, with the rollers in the positionsillustrated in FIGURE 6, the column would move downward in the directionof the arrow H. As the rollers move in opposite directions towardspositions diametrically opposite to that shown, the forces cancel outuntil the extreme opposite position is reached at which time the sum ofthe force vectors act in the direction of the arrow G to move the columnin that direction. With this system, solely oscillatory movement of thecolumn is obtained for completing the weld at the resonant frequency ofthe latter.

It should be noted that the vibrators employed with each of the devicesdescribed above obtains a frequency multiplying effect. Reference ismade to the patent to Svenson 2,194,410 for a full explanation of thisfeature; however, for present purposes suffice to say that the frequencymultiplication occurs whenever the roller is of a diameter greater thanone-half the diameter of the confining chamber. With this relationship,for each complete revolution of the roller about its axis, a number offorce impulses greater than one occurs against the housing of thevibrator.

Various changes and modifications can be made in the above-describedstructures without departing from the spirit of the invention. It shouldbe understood that such changes and modifications are contemplated bythe inventor and he does not intend to be limited except by the scope ofthe appended claims.

What is claimed is:

1. Apparatus for welding metal members together comprising a pair ofcolumns having end portions between which said members to be welded aredisposed, means for moving one of said columns into end portion contactwith said members so as to apply a predetermined force in one areathereof, the other column formed with a confining chamber which islocated on an axis offset from the column axis, a mass disposed in saidchamber and adapted to orbit about the chamber so as to create arotating force vector in a plane normal to said column axis, and meansfor driving said mass in said orbital path at a frequency which causessaid column to resonate in a standing wave with torsional andoscillatory bending whereby vibratory energy is directed to said onearea to form a weld between the members.

2. The apparatus of claim 1 wherein said means for driving said mass isa pressurized fluid.

3. Apparatus for welding metal members together comprising a pair ofaligned columns having end portions between which said members to bewelded are disposed, means for moving one of said columns into endportion contact with said members so as to apply a prepredeterminedforce in one area thereof, the other column formed with a circularconfining chamber which is disposed on an axis offset from the columnaxis, a mass disposed in said chamber and adapted to orbit about thechamber so as to create a rotating force vector in a plane normal tosaid column axis, a source of pressurized fluid, and a plurality ofpassages circumferentially spaced about the chambers for directingpressurized fluid from said source as a high velocity stream against themass so as to drive said mass in said orbital path about the confiningchamber at a frequency which causes said column to resonate withtorsional and oscillatory bending whereby vibratory energy is directedto said one area to form a weld between the members.

4. Apparatus for welding metal members together comprising a pair ofaligned columns having end portions between which said members to bewelded are disposed, means for moving one of said columns into endportion contact with said members so as to apply a predetermined forcein one area thereof, the other column formed with a circular confiningchamber which is disposed on an axis offset from the column axis, aroller-type mass disposed in said chamber and adapted to orbit about thechamber so as to create a rotating force vector in a plane normal tosaid column axis, means for driving said mass in said orbital path aboutthe confining chamber at a frequency which causes said column toresonate and cause torsional and oscillatory bending in the end portionof said column whereby vibratory energy is directed to said one area toform a weld between the members, and means associated with each of saidcolumns to permit a minimum of energy loss from the columns.

5. Apparatus for welding metal members together comprising a pair ofaxially aligned columns having end portions between which said membersto be welded are disposed, air-operated means for moving one of thecolumns into end portion contact with the members to apply apredetermined force in one area thereof, the other column formed with apair of integral arms extending laterally from opposite sides of saidcolumn, a confining chamber disposed in each arm on an axis offset fromthe column axis, a roller-type mass in each of the confining chambers, asource of pressurized air, air passage means formed in thelast-mentioned column connecting the source with the confining chambersand including ports circumferentially surrounding each mass fordirecting pressurized air at a tangential direction against the latter,and means for controlling the air flow from the source to the confiningchamber so that each mass is driven at a frequency which causes thecolumn to resonate in a torsional mode and transfer sufficient vibratoryenergy to said one area to form a weld between the members.

References Cited by the Examiner UNITED STATES PATENTS 2,496,291 2/1950High 2591 2,522,906 9/ 1950 Smith 2591 2,707,889 5/1955 Sowter 29-470.12,937,292 5/1960 Welkowitz 2591 2,946,119 7/1960 Jones 7882 2,960,31411/1960 Bodine 259-1 3,017,792 1/1962 Elmore 78--82 3,039,333 6/1962Jones 78-82 3,052,020 9/1962 Jones 29--470.1 3,054,309 9/1962 Elmore78-82 CHARLES W. LANHAM, Primary Examiner.

WILLIAM W. DYER, IR., WILLIAM J. STEPHEN- SON, Examiners.

1. APPARATUS FOR WELDING METAL MEMBERS TOGETHER COMPRISING A PAIR OFCOLUMNS HAVING NED PORTIONS BETWEEN WHICH SAID MEMBERS TO BE WELDED AREDISPOSED, MEANS FOR MOVING ONE OF SAID COLUMNS INTO END PORTION CONTACTWITH SAID MEMBERS SO AS TO APPLY A PREDETERMINED FORCE IN ONE AREATHEREOF, THE OTHER COLUMN FORMED WITH A CONFINING CHAMBER WHICH ISLOCATED ON AN AXIS OFFSET FROM THE COLUMN AXIS, A MASS DISPOSED IN SAIDCHAMBER AND ADAPTED TO ORBIT ABOUT THE CHAMBER SO AS TO CREATE AROTATING FORCE VECTOR IN A PLANE NORMAL TO SAID COLUMN AXIS, AND MEANSFOR DRIVING SAID MASS IN SAID ORBITAL PATH AT A FREQUENCY WHICH CAUSESSAID COLUMN TO RESONATE IN A STANDING WAVE WITH TORSIONAL ANDOSCILLATORY BENDING WHEREBY VIBRATORY ENERGY IS DIRECTED TO SAID ONEAREA TO FORM A WELD BETWEEN THE MEMBERS.